Exercise on observing load balancer weightings
The load balancer spreads the load across real servers, and can be configured so that the load on each server is weighted, e.g. with 80% of the load being sent to one server, and 20% of the load being sent to another server. In this exercise, you will measure the performance of the ??system?? to determine the weightings that the load balancer gives to each server. Note that there are 2 servers and the weightings must add to 100%. Part 1: Local monitoring In this exercise, you will generate HTTP traffic on a computer, and that traffic will pass through the load balancer to one of 2 HTTP servers. The load balancer mirrors the traffic that it sends to the servers onto another port which is also connected to the computer from which you generate traffic, so you can observe the traffic going to the servers on the same computer that you use to generate the traffic. #Configure the load balancer using TFTP to load the file "load#" where # is the last digit of your student ID. #Use TeamViewer to access the GUI of the ?? server (192.168.200.150). #Open Wireshark on the server by typing "sudo wireshark" from a terminal. #Configure Wireshark's display filter to only show the traffic going to one of the HTTP servers by typing "ip.dst 192.168.100.151 && http" in the display filter field and press "enter" to apply the change. #Open the HTTP Traffic Generator. Enter http://192.168.200.100 as the URL, and set the count (of requests to be generated automatically) to 1000. Set the Interval (how often the HTTP requests are sent) to be as low as possible (i.e. 1 ms) so that the experiment is as fast as possible. The traffic generator should appear as shown in the screenshot. #Check that Wireshark is capturing packets, then press Start on the traffic generator. #When the traffic generation is complete, check how many of the 1000 requests sent were received by the 192.168.100.151 server; the remaining requests would have been received by the other server. From this you can determine the weightings that the load balancer has been configured to give each server. Record your finding in the !!!results forum. Part 2: Remote monitoring #Load the "RMON-MIB" into the MIB Browser #Read the etherStatsPkts count (OID .1.3.6.1.2.1.16.1.1.1.5) in the RMON etherStatsTable for each port of the load balancer. Record your answers (you can ignore ports with 0 packet counts), and the current value of the sysUpTime object in the results form. The port that has the highest count is on the client side, and the other ports are on the side of the servers. #Repeat the instructions above to use the traffic generator to send 1000 packets to the servers. However, this time there is no need to use Wireshark to capture and analyse the packets. Instead, when the traffic generator has finished, repeat step 2 to read the packet counts as collected by RMON. Record your finding in the !!!results forum.